This invention relates to the transportation of limp material segments, such as fabric. In particular, the invention relates to an apparatus for frictionally engaging limp material segments for transportation along a work surface.
Conventional techniques for transporting limp material segments along a work surface to a workstation often utilize manual labor. In the context of the textile industry, garment assembly personnel may manually feed the fabric workpiece or workpieces along a work surface to the sewing head of a sewing machine. Although many aspects of the textile industry benefit from automation, in practice transportation of fabric workpieces for assembly at a sewing machine largely remains dependent upon manual labor.
A primary shortcoming of the use of manually controlled workpiece transport is that the technique is enormously labor intensive; that is to say, a large portion of the cost to manufacture a product from limp material is attributable to labor. To reduce cost, techniques focusing on automation of transporting a limp material segment is desirable.
There are several known techniques for precisely controlling the position of the workpiece in the near-field region of the sewing head, see, for example, U.S. Pat. No. 4,719,864. Feed dog assemblies have also been used for this function. Those controllers however are generally so limited in their range of operation that other techniques are required to feed the workpiece to the effective range of the near-field controllers.
There are also known techniques for automatically (e.g. under the control of a programmed computer) driving endless belts to transport limp material workpieces over relatively large distances to workstations, see, for example, U.S. Pat. Nos. 4,457,243, 4,512,269, 4,032,046 and 4,607,584.
However, the endless belt techniques, which are particularly effective for control of gross motion control of workpieces are limited in their applicability to relatively short range motions necessary, for example, to present fabric to the near-field controller of an automated sewing machine. Therefore, there exists a need for improved systems for controlling the transport of limp material segments, particularly for application where linear feed control is needed to drive a workpiece to a position within the range of a near-field controller for a seam joining assembly.